1. Field of the Invention
The disposal of solid waste material, particularly hazardous waste material, is a continuing problem. Hazardous waste materials must be properly handled to avoid damage to humans and the environment.
This invention relates to a method and apparatus for making solid waste material environmentally safe using heat. More particularly, this invention relates to a method and apparatus for continuously modifying solid waste material to a ceramic-like composition using heat at high temperatures. The process is initiated by coherent radiation and sustained by an excitation material.
The solid waste may itself be the product of prior combustion such as incinerator ash, especially fly ash. The ash or like material is processed with combustible excitation material which itself may be a waste material. Another example of solid waste material is metal waste including items such as used paint cans, white appliances, waste steel with waste oil, aluminum stampings, all in the form of chips.
The combination of combustible excitation material and the products of prior combustion are heated to sufficient temperature to reduce the waste to a harmless disposable ceramic-like material and an effluvia of gas and particulates in the presence of oxygen. The effluvia is cleansed of remaining harmful materials, such as heavy metals, and otherwise processed for safe disposition into the atmosphere. The ceramic-like product of the present invention is crystal-like hard material which is environmentally safe.
Incineration of waste material is a principal method of waste disposal. However, the ash by-product of incineration (commonly called fly ash and bottom ash) is itself considered to be a undesirable waste since it contains heavy metals and other hazardous substances such as arsenic and organic compounds such as dioxins. Such substances are dangerous to humans and will contaminate the environment unless the ash is disposed of in a safe manner. Safe disposal is costly and represents an ever present risk to the environment. It is therefore desirable to provide a method and apparatus for further transforming ash and other solid wastes to materials which are suitable for environmentally safe disposal or even as useful products. It is also desirable to provide a method and apparatus for the transformation of solid waste materials considered to be extremely hazardous such as solid medical wastes. The present invention is directed to a method and apparatus for the transformation of such solid waste materials using heat applied at high temperatures.
2. Description of the Prior Art
Methods and apparatus for reducing materials to separable constituents, including waste materials, using coherent radiation have been proposed in the past, but none is known to be commercially in use. The modification by pyrolysis of solid materials in a plasma is also known, although such plasmas are not necessarily initiated by directing coherent radiation at the material to be modified.
Other deficiencies in high temperature waste treatment processes have limited their utility. These involve difficulties in processing the effluvia of the combustion process which are themselves hazardous and therefore have required costly special treatment. Other deficiencies are that gas/electrode plasma systems have very limited duty life, i.e., 50 hours is the average life-time expectancy.